"We cannot sit this one out," Obama told the crowd, pegged at 26,500. That's nearly 10,000 more than turned out for a 2008 rally in the same location.

"We can't let this country fall backwards because the rest of us didn't care enough to fight," Obama said. "I'm going to get out there and fight as hard as I can."

Also of note, embattled Sen. Russ Feingold (D-WI) showed up for the rally after all. His aides had told TPM he'd need to be in Washington for Senate business, prompting GOP cries that Feingold didn't want to be seen with Obama.

But after votes finished up, Feingold headed home to attend. Obama gave him a shoutout.